Google appears to be testing a new Google Instant search feature known as Instant Search Within. I've seen this feature within unofficial search browser extensions but it seems Google is now testing it directly in Google.

So how exactly does it work?

You look up some brand and then Google will show you an instant suggestion for brand name plus "search within." As you can clearly see from the screen shot, provided by techno-net's video, this will do a site command search for a keyword phrase within CNN.com.

Here is the video demonstration:

Would Google retain this? I am not sure, they already abandoned other search within attempts in the past.